In the US, S. aureus is the most common etiologic agent in systemic infection and in biofilm-mediated infection of implanted devices. Treatment is complicated by the steady emergence of antibiotic resistance and by increases in elderly, immunocompromised populations, prevalence in the use of surgically implanted devices, and by the ability of both resistant and susceptible strains to persist asymptomatically months to years after the withdrawal of antimicrobial therapy. Severe infection is associated with high rates of mortality (11%-43%) and with chronic, debilitating morbidities that include infective endocarditis, osteomyelitis, and recurrent lung infection. The current cost-of-care is estimated at $10 billion annually for treatment of infection by methicillin resistant S. aureus (MRSA) alone.
S. pyogenes is the cause of many human diseases, ranging from mild skin infections to life-threatening systemic diseases. An estimated 700 million infections occur worldwide each year, and over 650,000 cases of severe, invasive infections that have a mortality rate of approximately 25%.
Strategies for improving treatment options for S. aureus and S. pyogenes have included the creation of new antibiotics and the development of adjunctive therapeutics.